<div>
  <button type="button" (click)="test_ngClass()" >ngClass</button>
  <div>
    <p [ngClass]="this.currentClass">中国</p>
  </div>
</div>

<div>
  <button type="button" (click)="test_class_yellow()" >class.xxx</button>
  <div>
    <p [class.test_class_yellow]="this.p_yellow_status">中国福建</p>
  </div>
</div>

<div>
  <button type="button" (click)="test_ngStyle()">ngStyle</button>
  <div>
    <p [ngStyle]="this.currentStyles">中国你好</p>
  </div>
</div>

<div>
  <button type="button" (click)="test_style_yellow()">style.xxx</button>
  <div >
    <p [style.font-size]="p_style_yellow_status">福建你好</p>
  </div>
</div>

